Fabrication of (Bi0.5K0.5)TiO3 modified BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 piezoelectric ceramics

The lead-free x(Bi0.5K0.5)TiO3-0.23BaTiO3-0.02Bi(Mg0.5Ti0.5)O3-(0.75-x)BiFeO3 piezoelectric ceramics (x = 0.05, 0.07, 0.09, and 0.11) were prepared by solid-state reaction method. The increase of (Bi0.5K0.5)TiO3 concentration revealed a decrease of dielectric maximum temperature (Tm), however, the values were higher than 420 ?C. The Rietveld structure refinement for each composition showed pseudo-cubic symmetry and the rhombohedral distortion (90 - ?F) was gradually decreased from 0.27? to 0.09? for x = 0.05 and 0.11, respectively. The saturation and remanent polarization were increased and a coercive field was decreased, while the critical exponent (?) was increased from 1.407 (x = 0.07) to 1.821 (x = 0.11) revealing more relaxor-like behavior with higher (Bi0.5K0.5)TiO3 content. The remanent polarization, coercive field, and piezoelectric strain constant of 31.9 ?C/ cm2, 23.6 kV/cm, and 315 pm/V, respectively, obtained in the composition with x = 0.11 are significantly higher than those reported previously for other Bi-based piezoelectric ceramics with Tm>250 ?C.

Automated summary

Lead-free piezoelectric ceramics were prepared with the addition of (Bi0.5K0.5)TiO3 and BiFeO3 components via solid-state reaction method. The study found that increasing the concentration of (Bi0.5K0.5)TiO3 can enhance the piezoelectric performance of the material while reducing the dielectric maximum temperature.